AutoCodes – Lexus – P0748 Lexus

P0748 Lexus Code - Pressure Control Solenoid 'A' Electrical

Quick Answer

Changing from 1st to 6th is performed by the Engine Control Module (ECM) turning shift solenoid valves SL1, SL2, SL3, SL4, and SL on and off. Common causes include Low transmission fluid level, Dirty transmission fluid, Faulty Pressure Control Solenoid 'A' valve (Shift Solenoid Valve SL1). Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: P0748 Lexus indicates Pressure Control Solenoid 'A' Electrical.
Common causes: Common causes include Low transmission fluid level, Dirty transmission fluid, Faulty Pressure Control Solenoid 'A' valve (Shift Solenoid Valve SL1).
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

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Code Popularity 13,226

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Sep 11, 2022

Description
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
Comments
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Code P0748 Lexus Description

Changing from 1st to 6th is performed by the Engine Control Module (ECM) turning shift solenoid valves SL1, SL2, SL3, SL4, and SL on and off. If an open or short circuit occurs in any of the shift solenoid valves, the ECM controls the remaining normal shift solenoid valves to allow the vehicle to be operated.
This Diagnostic Trouble Code (DTC) indicates an open or short in the shift solenoid valve SL1 circuit. The ECM commands gear shifts by turning the shift solenoid valves on or off. When there is an open or short circuit in any shift solenoid valve circuit, the ECM detects the problem and illuminates the MIL, and stores the DTC. The ECM also performs the fail-safe function and turns the other normal shift solenoid valves on or off. (In case of an open or short circuit, the ECM stops sending current to the circuit.)
While driving and shifting between the 4th and 5th gears, if the ECM detects an open or short in the shift solenoid valve SL1 circuit, the ECM determines there is a malfunction.

OBDII Code P0748 Lexus - Pressure Control Solenoid 'A' Electrical - AutoCodes.com — P0748 Lexus Code - Pressure Control Solenoid 'A' Electrical

What does this mean?

What are the Possible Causes of the DTC P0748 Lexus?

Low transmission fluid level
Dirty transmission fluid
Faulty Pressure Control Solenoid 'A' valve (Shift Solenoid Valve SL1)
Pressure Control Solenoid 'A' valve harness is open or shorted
Pressure Control Solenoid 'A' valve circuit poor electrical connection
Faulty Engine Control Module (ECM)

How to Fix the DTC P0748 Lexus?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What does this mean?

Code Tech Notes

When a transmission solenoid malfunction, in most cases the problem is not the electrical part of the solenoid; the problem is foreign material obstructing the mechanical function of the solenoid or the flow of the fluid through the transmission valve body. If the transmission fluid is dirty, it's recommended to change the transmission fluid and if possible, remove the transmission pan for further diagnosis. Excessive debris or metal particles on the transmission pan could be an indication that there is a mechanical transmission failure, and that the transmission will need to be rebuilt or replaced.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0748 Lexus code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.